Towards a Personalized Organized Screening in Breast Cancer : Practical Determination of Thresholds of Risk in Women at Average-Risk

Abstract

In France, more than 10 million women at ”average” risk of breast cancer (BC), are included in the organized BC screening. Existing predictive models of BC risk are not adapted to the French population. Thus, we set up a new score in the French Hérault region and looked for a graded level of risk in women at "average" risk. We recruited a retrospective cohort of women, aged 50 to 60, who underwent the organized BC screening, and included 2241 non-cancer women and 527 who developed a BC during a 12-year follow-up period (2006-2018). The risk factors identified were high breast density (ACR BI-RADS grading)(B vs A: HR 1.41, 95%CI [1.05; 1.9], p=0.023; C vs A: HR=1.65 [1.2; 2.27], p=0.02 ; D vs A: HR=2.11 [1.25;3.58],p=0.006), a history of maternal breast cancer (HR=1.61 [1.24; 2.09], p < 0.001), and socioeconomic difficulties (HR 1.23 [1.09; 1.55], p=0.003). While early menopause (HR=0.36 [0.13; 0.99], p=0.003) and an age at menarche after 12 years (HR=0.77 [0.63; 0.95], p=0.047) were protective factors. We identified 3 groups at risk: lower, average, and higher, respectively. A low threshold was characterized at 1.9% of risk and a high threshold at 4.5%. Mean risks in the 3 groups of risk were 1.37%, 2.68%, and 5.84%, respectively. Thus, 12% of women presented a level of risk different from the average risk group, corresponding to 600,000 women involved in the French organized BC screening, enabling to propose a new strategy for performing an organized and personalized national BC screening.